Fueling environments are being subjected to increasingly rigorous statutes and regulations that prohibit fuel leaks and detail how leaks are to be detected within the fueling environment. One particular area in which leak detection is critical is in the storage tank in which the fuel is stored prior to sale. Such storage tanks, which are typically located beneath the ground, and thus, are commonly referred to as “underground storage tanks”, are typically equipped with a probe that measures the height of the fluid within the storage tank. Additionally, the probe may measure temperature, pressure, and other environmental factors that are used in determining the volume of fluid within the storage tank. These factors are then reported to a tank monitor or other site controller to determine if the tank is leaking and for inventory reconciliation.
In the past, the probe reported the factors and parameters through an electromagnetic signal sent over a wirebased system. While adequate for its intended purpose, such wirebased systems have at least two drawbacks. The first drawback to conventional systems is that the communication wires must be routed through an intrinsically safe conduit to reduce the risk of explosion. Such intrinsically safe conduit is expensive, raising the cost of compliance to the fueling environment operator. The second drawback to the conventional systems is that the communication wires must run from the underground storage tank to the tank monitor, which is usually located in the central office of the fueling environment. These communication wires are typically run underneath the concrete slab that forms the fueling environment's forecourt. If the communication wires are damaged or need to be replaced, the entire forecourt is disrupted as the concrete slab is broken, and the communication wires excavated. Thus, it is difficult to upgrade or repair existing systems without great expense and disruption to the ordinary course of business for the fueling environment.
The current leak detection statutes and regulations extend beyond just the underground storage tank and affect the entire piping system of the fueling environment. Thus, sumps associated with the piping system likewise have leak detection probes. These sumps may be positioned underneath the fuel dispensers, at low points in the piping system, or other locations as needed. The sump probes are usually liquid level sensors and generally lack some of the sophistication of the underground storage tank probe. However, this relative lack of sophistication does not lessen the complications associated with establishing the communication link to the tank monitor or other site controller. Specifically, the sump is considered to have the potential for fuel vapors therein, and thus, the environment must be intrinsically safe. The wiring for the sump probe is also usually run underneath the concrete slab of the forecourt. The intrinsically safe requirement and the need to run wires under the forecourt mean that such sump probes likewise increase expense for the fueling environment operator.
A few systems have proposed a wireless communication link between the tank probe and the tank monitor in an effort to alleviate costs associated with the conventional wire based systems. While seemingly simple in concept, such systems have run into implementation difficulties. Specifically, the large metallic bodies of cars that move around the fueling environment may create unpredictable capacitive and inductive elements in the signal path, thereby disrupting the signal path. In extreme cases, the cars may cause the signal to be canceled. Even when the impact of the cars does not cancel the signal, the concrete slab and other environmental factors help attenuate the signal from the probe such that the tank monitor's receiver does not receive an interpretable signal. While it is conceivably possible to boost the wireless signal from the probe sufficiently to overcome the variable attenuation of the forecourt, this is not always an optimal solution as more power is required to boost the signal in this manner. The wires and circuitry providing power to the sump may not be able to handle the increased load associated with the increased power supply. Even if the power level can be boosted to a level strong enough to reach the tank monitor, the signals with the increased power may exceed the emission limits permitted by the Federal Communication Commission (FCC).
Thus, an improved system is needed that allows sensors and probes within sumps to communicate wirelessly with the tank monitor or site controller of a fuel environment.